What Causes Erectile Dysfunction? Physical, Psychological and Medication Causes

Erectile dysfunction (ED) is the most common sexual health concern men report to their doctor, affecting as many as one in five men in the UK. It can occur in men of any age, though it becomes more common with age. Understanding the cause is the most important step toward effective treatment — because the right treatment depends entirely on what is driving the problem.

What Is Erectile Dysfunction?

Erectile dysfunction is characterised by the persistent inability to achieve and/or sustain an erection sufficient for satisfactory sexual intercourse. Occasional difficulties are normal — ED is a clinical concern when it occurs regularly, causes distress, or follows a consistent pattern over several weeks.

For a broader overview of ED and treatment options, see: Understanding and Overcoming Erectile Dysfunction.

Physical Causes of Erectile Dysfunction

At its most fundamental level, ED is caused by disrupted blood flow, nerve signalling, or hormonal balance in the erectile mechanism. The following conditions are common physical contributors.

Cardiovascular Disease

Atherosclerosis — the narrowing of arteries by fatty plaques — reduces blood flow throughout the body, including to the penile blood vessels. Because the arteries supplying the penis are smaller than coronary arteries, atherosclerosis often manifests as ED before it causes cardiac symptoms. New-onset ED in a man with cardiovascular risk factors is a marker worth taking seriously.

Diabetes

Diabetes causes both nerve damage (diabetic neuropathy) and blood vessel damage (diabetic vasculopathy). Both directly impair the erectile mechanism. ED affects approximately 50% of men with diabetes within 10 years of diagnosis, and up to 75% over a lifetime.

High Blood Pressure (Hypertension)

Sustained high blood pressure damages blood vessel walls over time, reducing their elasticity and impairing blood flow to the penis. Several antihypertensive medications also contribute to ED as a side effect — see the medication section below.

High Cholesterol

Elevated LDL cholesterol contributes to atherosclerosis and impairs endothelial function in blood vessels. A diet high in saturated fat and low in protective nutrients is associated with increased ED risk.

Hormonal Conditions

• Low testosterone (hypogonadism) — reduces libido and may impair erectile function directly
• Thyroid disorders — both overactive and underactive thyroid can affect sexual function
• Cushing’s syndrome — excess cortisol suppresses testosterone

Neurological Conditions

• Parkinson’s disease
• Multiple sclerosis
• Spinal cord injury
• Epilepsy and anti-epileptic medications
• Peripheral neuropathy

Obesity

Obesity drives ED through multiple overlapping mechanisms: it raises cardiovascular risk, disrupts hormone balance (higher body fat leads to lower testosterone and higher oestrogen), worsens insulin resistance, and directly impairs vascular function.

Sleep Apnoea

Obstructive sleep apnoea reduces overnight oxygen delivery and is associated with lower testosterone levels and increased ED risk. Treating sleep apnoea can improve erectile function.

Surgery and Trauma

Surgery affecting the pelvis or abdomen — particularly radical prostatectomy (prostate removal for cancer) — can damage the cavernous nerves that control erectile function. See our guide to surgery and erectile dysfunction for full detail on post-surgical ED, recovery timelines, and treatment options.

Peyronie’s Disease

Scar tissue (plaque) inside the penis causes curved, painful erections and can contribute to ED.

Psychological Causes of Erectile Dysfunction

Psychological factors are particularly prominent in younger men experiencing ED.

Performance Anxiety

The most common psychological cause of ED in younger men. One difficult sexual experience creates a self-fulfilling negative cycle: worry about failing → stress response during arousal → physiological impairment → erection difficulty → increased worry. The anxiety itself becomes the obstacle.

Depression

Depression reduces libido, lowers testosterone, and disrupts the neurological pathways required for sexual arousal. Many antidepressant medications also contribute to ED as a side effect.

Stress and Fatigue

Chronic stress — from work, finances, or relationships — elevates cortisol, which suppresses testosterone production and impairs sexual function. Acute fatigue can also cause temporary erectile difficulties that are self-resolving.

Relationship Problems

Communication difficulties, conflict, emotional distance, or intimacy issues within a relationship frequently contribute to ED. The problem becomes circular — ED strains the relationship, and relationship strain worsens the ED.

Excessive Pornography Use

Growing clinical evidence suggests that heavy, habitual pornography consumption can contribute to ED in some men — particularly younger men — through desensitisation to real-world sexual stimulation and the development of unrealistic expectations.

The Tissue Paper Test

A simple home assessment can give a rough indication of whether your ED may be primarily psychological. Wrap a thin strip of tissue paper around the flaccid penis at bedtime and secure with tape. If it has torn in the morning, a nocturnal erection occurred — which suggests the physical mechanism is intact and a psychological factor may be dominant.

This is a rough guide only and does not replace a clinical assessment. However, it can be a useful starting point for understanding which type of cause is more likely.

Medications That Can Cause ED

If you believe a medication is contributing to your ED, speak to your prescriber about alternatives. Do not stop any medication without medical guidance. For lifestyle approaches that address modifiable risk factors, see: Lifestyle Changes for Erectile Dysfunction.

When to Seek Assessment

See a doctor or prescriber if ED has been present consistently for more than 2–4 weeks, it is causing distress or affecting your relationships or quality of life, you have cardiovascular risk factors (diabetes, hypertension, high cholesterol, obesity), ED began after starting a new medication, or you are under 40 — in younger men, a thorough assessment is important to rule out underlying physical or hormonal conditions.

See also: symptoms of erectile dysfunction.